36" Pompeii build in NY

[UtahBeehiver]

Re: 36" Pompeii build in NY

Hey Don,

How is your brick jig working out? Once you clear the arch it get easier........

[bluecrow]

Re: 36" Pompeii build in NY

Hi,

Sorry to learn of your setback, but you're very close to closing in!

Using varying brick widths changes the bevel and angle a bit, so i have learned to trust my instincts while cutting with the jig pair, and then to trial fit most bricks. The math was reliable until a narrower brick was required to produce a stagger.

My next rig will match the jack and disc you are working with now.

[UtahBeehiver]

Re: 36" Pompeii build in NY

Those narrow brick, wider mortar gaps, slope angle not being spot on has a was of mucking with cutting consistent bricks with a jig. It get me close but end up custom fitting almost every one in the upper course. I am going to sneak out when the better half is not looking and see if I can work on the last course. There is some debate which car jack works best. I used a Suzuki other a Honda, LOL.

[bluecrow]

Re: 36" Pompeii build in NY

Going, going, gone ! The dome is closed. The last few courses went fast.

The dome needs a scrub inside and I missed a few staggers, and there are some wider joints than I realized, but I think it will cook.

I'll try to build the outer arch over the next few days.
I will provide a setback so a door can seal for baking. I am planning on a relatively narrow contact (~1 ") between the inner and outer arch for a thermal break. I'll use stove rope gasket to seal the space. The outer arch will be flush with the inner arch and they will likely separate a bit. If there is another way to go (at this point) please let me know.

Don

[UtahBeehiver]

Re: 36" Pompeii build in NY

Congrats Don on closing the dome. Jealous, I am still plugging along on the last course.

[bluecrow]

Re: 36" Pompeii build in NY

Thanks.

My smaller dome goes faster. There was a lot of climbing up to, and down from, the hearth today. An injury would be easy to incur.

I didn't use the jack and plate. I could see from the 8th course that I would not notice mortar gaps if the dome base was covered. I held a couple of bricks with sticks and wedges and then cleaned up a bit after the ring was complete.

[UtahBeehiver]

Re: 36" Pompeii build in NY

Don,

I actually reverted back to the IT and sticks, like you I could not see what was happening underneath the plywood disk, although easier and faster, I decided to go slower and able to get a visual alignment. I modified my IT to hold a smaller brick this week and going to give it a go this weekend. Good luck with you vent arch.

[vtsteve]

Re: 36" Pompeii build in NY

I built my inner vent arch *around* the "snout" of the dome. I back-cut the rear edges of the arch bricks to miss the dome, and chamfered the vent side to smooth the flow of smoke. There's a gap of ~0.1" all around the snout, and I packed the volume between the dome and the back-cuts with ceramic fiber.

[bluecrow]

Re: 36" Pompeii build in NY

Thanks Steve,

So I don't necessarily need as much (or any) mortar contact between the inner arch and the vent arch as I was planning.

[bluecrow]

Re: 36" Pompeii build in NY

I am posting this update with a question about heat management. I am trying to figure out if I need to weld up and install a throat adaptor to make the inner arch opening smaller.

I have been firing my oven for over three weeks. The most recent two got the floor to about 725 deg. F., but it is difficult to maintain floor temps over 625 without adding wood every ten minutes or so.

The oven is up to temp in about 90 minutes, but it uses much more wood than I thought it would need.

-No dome cracks (yet?), but a mortar crack appears in the vent arch on firing.

-The oven draws very well, even with a 6 " duratech (no smoke out the front).

I will build a decorative arch and a stone face on the front of the gabled house when I know that all is okay.

My arch dimensions are a bit greater than the ideal.

Floor diameter = 36.5 inches
max dome height = 19.0 inches
max inner arch height = 12 inches (63% of dome ht)
max inner arch width = 19 inches

2" of FB Board under the floor (The hearth center is at about 120deg after 5+ hours)
3" of FB blanket over the dome and arch. I will fill the gable with vermiculite later.

I know that the inner arch heights and width are slightly too large, but the arch is a catenary, not semi-circular, so the opening area is a bit smaller than most arches with the same heights and widths.

In short, I am guessing that I am losing lots of heat up the chimney. Does it seem like a smaller inner arch opening would imporve the oven function?

Don

[UtahBeehiver]

Re: 36" Pompeii build in NY

Long time Blue,

You have made some major headway with the build since your last post. Interesting temperature observations. I am in the early stages of curing so it will be interesting to see how my build behaves. Anyway at those temps you should be able to do some cooking. Nice enclosure so far.

[Laku]

Re: 36" Pompeii build in NY

How do you maintain the fire during the heating? Is it just in ones spot? Do you move it around? Where do you measure the floor heat? Do you start cooking straight away when the dome clears?

It doesn't sound like you're lacking insulation, and the inner arch height seems to be within specs. So those are unlikely to be your problem, unless there's moisture in your floor insulation.

The embers should cover most of the floor during the firing and be moved to side maybe 10-20 minutes before you plan on starting to cook depending on the floor heat.

It takes about 2 hours for my ~46" oven to reach 842 F floor temp. Dome clears in about 90 minutes. Longer the burn the more saturated the floor will get.

I usually use about 2-2,5 armful of firewood on a typical pizza night which includes maybe 1-1,5 hours of cooking.

It might help if you get some sort of fire rack that will elevate the fire higher and help the heat radiation to hit the floor from a better angle. It also makes it easier to move the embers around.



ps. I'm assuming you're talking about pizza temps.

[bluecrow]

Re: 36" Pompeii build in NY

Thanks for the replies.

I used more wood than in previous burns and spread the embers over the floor for a minute before each pizza.

The floor temps were ~750+ and pizza cooking time was in the 90 sec range.

I guess I do not need to modify the opening size. I'll get to work on the door and on the decorative arch and landing.

[vtsteve]

Re: 36" Pompeii build in NY

Since I started using a blast door (a misnomer; it doesn't have to "blast") I'm using less fuel and warming up faster. My door is a piece of 304 stainless with handles, which is shaped to fit against my vent arch when it's tipped back. It allows me to regulate the intake air (at the bottom) and the exhaust draft (how far it's tipped). I can still feel the door radiating heat, so I'll either insulate it or add a radiant shield inside. And a window... The extra heat that it retains promotes more complete combustion, too - the whole oven is a "rocket stove", so there's no need for plasma god fires.

[bluecrow]

Re: 36" Pompeii build in NY

Hi Steve,

I noticed that the profile of my cantilevered gable matches yours and that of (at least) one other member. I looked at so many builds I did not remember which informed my process the most.

Regarding the door, I understand the tilt/top regulation, but does the bottom have a cut out to allow air intake? I am not picturing the window at all.

I set up a few bricks at the door to reduce air flow at start-up, but your door sounds far better.

Don